The Legend of Grimrock Website has a launch week update, saying the dungeon crawler can still be had for its 10% preorder discount, and also outlining plans for the game's first patch, to address the following issues:

My only complaints so far are, like everyone else, the spell casting system, and that you can't use both hands to attack with. You can put different weapons in each hand, but you only get one attack and dual welding weapons doesn't seem to increase damage.

I loaded up Eye of the Beholder to refresh my memory, because I was pretty sure in EOB you could attack with each hand separately, and I was right. I also thought you equipped spells and cast them like weapons, and I was partially right. When you rest you have to pray/memorize spells. Depending on character level, you can only "load up" so many, for example you can do 4 level 1 spells and 2 level 2 spells. They can be different or the same, like 4 magic missiles, or 2 magic missiles and a 2 flame blade spells. Once you use them, you have to rest to "re-load" them.

I like that in Grimrock you don't have to rest to pray/memorize spells and can just cast until you run out of energy, but having to remember which symbol to select every time before casting is tedious. I wish it would at least remember the last spell you cast so you can continue to cast it rather than have to click each symbol every time before casting. It would be nice to have a spell book in game that you could reference to see what spells you have learned or figured out instead of having to remember them or write them down and look them up if you forget.